Voltage supplies to computer systems should ideally be consistently accurate and reliable and preferably without transients, such as voltage peaks and troughs, since these can cause faults in the operation of the computer system, for example hangs, panics and hard disc drive failures, causing undesirable interruptions and errors. Such failures often seem unrelated to power transients since accurate correlation is very difficult to establish. The number of separate voltage supply rails needed inside computer systems is increasing and at the same time the accuracy required for correct operation of the systems is rising.
Known systems monitor supply rails, for example using analogue-to-digital converters, but it is currently difficult usefully to correlate the data collected since this requires the operator constantly to monitor the converter output and, in any case, many problems seem unrelated unless they are persistent.
There is therefore a need for more exact monitoring of the voltage supply rails so as to provide more accurate information for fault diagnosis, and for monitoring in such a way that the information can be correlated to the faults arising.